Universal Astrolabe Juan de Rojas

Desde: 261,36

Universal astrolabe valid for use at any latitude. The perfect gift for astronomy and science lovers

SKU: P-220 Categories: ,
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The universal astrolabe had a great development during the 16th and 17th centuries in the city of Leuven in Belgium, which was at that time the most important center for astrolabe manufacturing and also for experts in astronomy. Leuven  had it all: access to scholarly and specialized writings on astronomy, good raw materials, and skilled craftsmen.


Two different styles of universal astrolabe emerged from this environment, with Genma Frisius (1508-1555) being the most influential astronomer in the development of both. He was directly responsible for popularizing the universal stereographic astrolabe which he called “Astrolabum Catholicum”, Frisius was a teacher of Juan de Rojas y Sarmiento, who documented a form of universal astrolabe that used orthographic projection, which became known as the astrolabe of Rojas.

A common so-called planispheric astrolabe requires a separate dish for each latitude, which makes it an impractical instrument to be used anywhere. Gemma Frisius designed an instrument in which one side was occupied by a planispheric astrolabe and on the other she adopted a form of astrolabe that could be used at any latitude. This instrument made a lot of sense, since there are problems that can be better solved with one or another concept of the astrolabe.

Gemma Frisius’s study of the “Astrolabum Catholicum” led directly to research into using another method of projections to lead to the conception of a Universal Astrolabe. One obvious projection to investigate was the orthographic projection.


Juan de Rojas, who was a student of Gemma Frisius, combined the relevant theories to create a form of universal astrolabe that used orthographic projection. Almost nothing is known about his life, but it is believed that he was born between 1520-1525 and that he was the second son of the first Marquis of Poza and it is said that he began his ecclesiastical career and became a bishop.

It is also not known when and how much time Juan de Rojas spent in Leuven, but it is almost certain that he lived there during the year 1544. Rojas returned to Spain shortly after, where he wrote his book on the orthographic astrolabe, which was published in Paris. in 1550. It is illustrated with 63 diagrams on the construction and use of the astrolabe described in the text. Apparently, after publishing his book he abandoned scientific studies and enlisted in the military.

He died on a trip to Thrace, but it is unknown exactly when and why he was there.


We have two presentations for this astrolabe:

-With a wooden base

-With a wooden frame

In a beautiful case that also includes instructions and examples for use.



Height (maximum measurement) 250 mm

Diameter: 200mm

Thickness: 8mm



Additional information

Weight 5 kg
Dimensions 0,4 × 0,25 × 0,15 cm


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